Compatible Ferroelectricity, Antiferroelectricity and Broadband Emission for a Multi-Functional 2D Organic-Inorganic Hybrid Perovskite

Two-dimensional (2D) organic-inorganic hybrid perovskites with multifunctional characteristics have potential applications in many fields, such as, solar cells, microlasers and light-emitting diodes (LEDs), etc. Here, a 2D organic-inorganic lead halide perovskite, [Br(CH 2 ) 3 NH 3 ] 2 PbBr 4 ( BPA-PbBr 4 , BPA = Br(CH 2 ) 3 NH 3 , 3-Bromopropylamine), is examined for its photophysical properties. Interestingly, BPA-PbBr 4 reveals five successive phase transitions with decreasing temperature, including successive paraelectric-ferroelectric-antiferroelectric phases. Besides, BPA-PbBr 4 displays ferroelectricity and antiferroelectricity throughout a wide temperature range (<376.4 K) with accompanying saturation polrization ( P s ) values of 4.35 and 2.32 μC/cm 2 , respectively, and energy storage efficiency of 28.2%, and also exhibits superior second harmonic generation (SHG) with maximum value accounts for 95 % of the standard KDP due to the great deformation of structure (3.2302*10 -4 ). In addition, the photoluminescence (PL) of the BPA-PbBr 4 exhibits abnormal red-shift and blue-shift in different phases due to a consequence of competition between electron-phonon interaction and the lattice expansion. Further, BPA-PbBr 4 reveals a broadband emission accompanied by bright white light at room temperature (293 K), which is supposed to be due to self-trapped excitons. In short, the versatility of BPA-PbBr 4 originates from molecular reorientation of dynamic organic cations, as well as significant structural distortion of PbBr 6 octahedra. This work paves an avenue to design new hybrid multifunctional perovskites for potential applications in the photoelectronic field.